Unidirectional flow rotary pump



Jan. 12, 1965 T. w. PHELPS ETAL UNIDIRECTIONAL FLOW ROTARY PUMP 2 Sheets-Sheet 1 Filed July 11, 1962 /Z Jan. 12, 1965 Filed July 11, 1962 1 W. PHELPS ETAL UNIDIRECTIONAL FLOW ROTARY PUMP 2 Sheets-Sheet 2 :2 E INVENTORS.

United States Patent 3,155,066 UNID$ECTINAL FLGW RSTARY PUMP Thomas W. Phelps, York, Pa, and James A. Short, Anna, Ohio, assignors to (Iopeiand Refrigeration Corporation, Sidney, @hio, a corporation of Michigan Fiied .Iuiy 11, I962, Ser. No. 2%,143 5 Claims. (Cl. 103-126} This invention relates to a rotary pump capable of producing unidirectional fluid flow, and particularly concerns improved reversing means for the pump for maintaining unidirectional pump output in installations where reversal in the direction of rotation of the pump drive occurs.

Many types of reversible rotary pumps are known and employed in such apparatus as compressors and the like for supplying lubricating oil thereto. The reversibility of these pumps is necessitated by the fact that the direction of rotation of the pump drive is dependent upon the manner in which the prime mover is connected to the main drive mechanism of the apparatus. The manner in which this dependency is created is explained below.

In a refrigeration motor-compressor unit of the type used on trucks for refrigerating the cargo space thereof, the main drive mechanism comprises an interconnected or unitary electric motor rotor and compressor crankshaft. A belt pulley is connected to one end of the crankshaft which extends out through the compressor housing. During operation of the truck, the pulley is connected to and driven by an external prime mover such as the truck motor or an auxiliary internal combustion engine mounted on the truck. When the truck is parked at a loading or unloading dock, the pulley is disconnected from the external prime mover by suitable means such as a magnetic clutch or equivalent device. It is seen, therefore, that the manner in which the external prime mover is connected to the pulley will determine the direction of rotation of the pump drive. Moreover, where the electric motor is of a type, such as the 3-phase current operative, which will start in either direction depending on the manner in which the electrical connections are made to the dock power supply, it is seen that the direction of rotation of the pump drive is dependent upon these connections. Such S-phase motors are also employed in hermetic motor-compressor units and create the same problem therein.

Many forms of reversing devices have been devised for these rotary pumps; however, generally speaking, these devices have experienced certain drawbacks such as slowness or uncertainty in responding to reverse rotation 'of the pump drive, excessive cost of manufacture, excessive complexity and size.

Typical rotary gear type pumps to which the present invention is readily adapted are shown, for example, in Neeson Patent Nos. 2,151,482 and 2,225,228. In these patents are also shown two types of pump reversing devices which are exemplary in their operation of a great many forms of such devices. In the first Neeson patent, a rotatable member is maintained in frictional engagement with the lower faces of the outer and inner gears of the pump. Fluid channels are formed in this member and as the member is rotated through a certain angle in response to a reversal in the direction of rotation of the pump drive, these channels are properly aligned with the inlet and outlet of the pump to maintain unidirectional pump output. In the second Neeson patent a crescentshaped member is carried by means also frictionally engaged with the lower faces of the pump gears. This means is caused to rotate in response to a reversal in the direction of rotation of the pump drive to engage and shift the inner gear of the gear pair to a position which properly positions the pumping cavity formed between idfiidhh Patented Jan. 12, I965 ice the gears relative to the suction and discharge ports of the pump to provide unidirectional pump output.

The above discussion of two exemplary forms of reversing devices is intended to indicate the general approach heretofore taken in shifting portions of gear pumps for maintaining unidirectional pump output. This approach has also been used for sliding vane-type pumps to which the present invention is also readily adaptable. It is seen that this approach utilizes only the friction between the reversing mechanism and the smooth face portions of rotating parts of the pump to impart rotating force to the reversing mechanism. Various aids such as the springs shown in the Neeson patents are employed to increase this friction to develop more positive response of the reversing mechanism to a change in the rotational direction of the pump gears. Such aids, however, increase the complexity, size and cost of the pump. Moreover, even with such aids, excessive friction in the reversing device may retard or even prevent its operation and result in a lubrication loss to the apparatus.

A principal object of the present invention, therefore, is to provide a rotary pump having improved reversing means for insuring unidirectional fluid output.

Another object is to provide simple and etfective means for imparting a highly positive rotating force to the reversing device of a rotary pump for increasing the response of the device to changes in the direction of rotation of the pump drive to insure unidirectional fluid flow.

Another object isto simply and inexpensively incorporate a pump of the above character in a motor-compressor unit.

Another object is to provide a structurally simplified, rugged and low cost pump having the above desirable operating characteristics.

Another object is to reduce the size of reversible type rotary pumps.

In abroad sense, these objects are accomplished by so constructing the reversing device that the friction de veloped for rotating the same to its operative positions is of a magnitude many times greater than the friction resisting such rotation. In a more limited sense these objects are accomplished in accordance with the preferred embodiment of the invention by utilizing the weight of the main drive mechanism of the apparatus for developing the friction necessary for rotating the reversing device. In the preferred embodiment, the reversing device is, during rotation to its operative positions, actually clamped to the main drive mechanism.

Further objects, advantages and novel features of the invention will become apparent from the following description, claims and drawings wherein:

FIGURE 1 is a bottom view of a motor-compressor unit;

FIGURE 2 is a longitudinal sectional view of the structure of FIGURE 1 taken along the line 22, showing the unit contained in a shell with the pump immersed in an oil sump;

IGURE 3 is a cross-sectional view of the structure of FIGURE 2 taken along the line 3-3;

FIGURE 4 is a cross-sectional view of the structure of FIGURE 2 taken along the line 4-4 showing one operative position of the reversing device and pump gears;

FIGURE 5 is a View similar to that of FIGURE 4 showing the other operative position of the reversing device and pump gears;

FIGURE 6 is a plan view of an eccentric gear retainer;

FIGURE 7 is a bottom plan view of a reversing plate;

FIGURE 8 is a cross-sectional view of the plate of FIGURE 7 taken along the line 88;

FIGURE .9 is a plan view of a thrust plate;

FIGURE 10 is a top plan view of a modified form of eccentric gear retainer;

FIGURE 11 is a cross-sectional view of a portion of thed retainer of FIGURE taken along the line 11I1; an

FIGURE 12 is a plan view of a modified form of the reversing plate foruse in conjunction with the retainer of FIGURES 10 and 11.

Referring to the drawings, a motor-compressor unit shown partially in FIGURE 2 and generally designated at 14 comprises an electric motor, not shown, of the type which may start in either direction, having its rotor connected to or formed integrally with the crankshaft 15 of a compressor 16. This motor-compressor unit may be of any well-known construction such as that shown, for example, in the aforesaid Neeson Patent No. 2,225,228. The unit is contained in a shell 18, the lower portion of which, as shown, provides a sump for lubricating oil ill. The compressor is of such construction that it may properly operate regardless of the direction of rotation of its crankshaft. The rotational axis of the compressor crankshaft is shown to be vertical, but as will hereinafter become evident, the present invention may also be incorporated in motor-compressor units wherein the crankshaft axis is horizontally disposed.

The end 22 of the crankshaft is rotatably supported in a bushing 24 frictionally secured in an aperture 26 of a cover 28 suitably bolted to the housing of the unit and sealing the open end 30 thereof. The crankshaft is provided with a main oil conducting passage 32 extending from the end portion 22 thereof inwardly through the crankshaft and connecting into branch lubricating passages 34- leading to the compressor connecting rod bearings and other movable portions of the unit. End portion 22 is formed with an annular recess 36 concentric with the rotational axis of the crankshaft and cooperates with an annular recess 38 in the housing cover 28 and concentric with recess 36 to provide a pocket in which the rotary pumping means and reversing means are contained. This pocket is closed except for inlet and outlet port means by a thrust plate 41 shown in FIGURE 9 and a cap 42 which is secured to the cover 28 by suitable screw means 44.

The rotary pumping means comprises an inner driving gear 46 and an outer idler gear 48. Gear as is provided with eight teeth and gear 48 with nine teeth to provide a pumping cavity generally designated at 49 and which is shiftable as will hereinafter become evident. Gear 46 is keyed to the crankshaft by means of a keying pin 50; however, this gear is axially slidable on the adjacent portion of the crankshaft for a purpose hereinafter explained. Rotation of driving gear 46 causes rotation of idler gear '48 so that pumping cavity 49 is continually formed by the teeth of these moving gears during pump operation.

The pump reversing device, as shown in FIGURE 2, comprises an eccentric gear retainer 52 and a reversing plate 53 which is slidably but frictionally clamped between the upper'surface of driving gear 46 and the laterally extending surface 51 of shaft end 22 forming the upper portion of recess 36. Further explanation of the structure and operation of this reversing device will appear herein. Retainer 52 is provided with a smooth inner circular surface 54, seen in FIGURE 6, which slidably but snugly engagesthe smooth outer circular surface of idler gear 48. Inner surface 54 is eccentric to the rotational axis of the crankshaft and to the outer surface 56 of the retainer which thereby makes the inner surface 54 a camming surface operable to shift idler gear 48 as the retainer rotates in recess 38. The outer surface 56 of the retainer is partially cut back from its original dimension indicated by the dotted line in FIGURE 6 to form the arcuate surface 58 terminating in a pair of shoulders 60 tween shoulders 60 and 62 which are 180 apart. A notch 66 is formed in the inner surface 54 of the retainer opposite an intermediate portion of surface 58 for a purpose hereinafter explained.

The fluid flow paths through the pump are defined by an arcuate suction port 68 in cap 42, seen in FIGURES 1, 2 and 3, an overlapping arcuate suction slot Fe in thrust plate 40, visible in FIGURES 2 and 9, the pumping cavity 4i between the gear teeth, an arcuate discharge slot '7 2 in plate 4-0, an interconnected arcuate recess 74 and lateral recess 76 in cap 42, and a central aperture 78 in thrust plate 50. In the operation of the pump, the oil flow is progressively through suction port 68, slot 7%}, pumping cavity 49, solt 72, recesses 74 and 76, and through aperture 73 into passage 32 of the crankshaft.

The reversing plate 53, seen in FIGURE 7, is formed With a central aperture 82 sufficiently large to accommodate the crankshaft end 22 and the keying pin St for free rotation. The outside diameter of the plate is such that its outer periphery will not frictionally engage the motion limiting pin 64 during relative rotation of the plate and crankshaft. Plate 53 is provided with a downwardly extending tang 84 which is positioned in the notch 66 of the retainer 52 and causes rotation of the retainer in response to rotation of the plate. As mentioned above, the inner gear 45, though keyed by pin 50 to the crankshaft, is axially slidable on the outer end portion 86 of the crankshaft to compress plate 53 between surface 5i on the shaft and the upper surface of the driving gear 46. Gear 45 and shoulder 51 in effect provide carrier means for plate 53. It is noted that portion 86 of the shaft is slightly less in length than the combined thicknesses of plate 53 and gear 46 to thereby allow compression of member 53. Also, annular recess 38 in cover 23 is willciently deep to prevent excessive frictional engagement of the top of plate 53 with the cover.

In the operation of the pump and its reversing means, upon starting of the compressor motor with the rotation of the compressor crankshaft in a clockwise direction as shown in FIGURE 4 and with the idler gear 48 and the reversing means in the position shown in FIGURE 5, the following occurs: With the combined weight of the compressor crankshaft and the other structure attached thereto bearing upon the reversing plate 53 and gear 46, plate 53 is frictionally clamped between surface 51 of the crankshaft and gear 46. It is seen, therefore, that rotation of the crankshaft and gear 46 in a clockwise direction will actually tend to carry plate 53 in a clockwise direction and rotate retainer 52 from the position shown in FIGURE 5 to the position shown in FIGURE 4. During this rotation of the retainer, the high side 86 of the camming surface 54 urges the idler gear 48 from its position shown in FIGURE 5 to the position shown in FIGURE 4. The pin 64 will engage shoulder 62 to limit rotation of the retainer and thereafter hold it and plate 53 stationary while the crankshaft and gear 46 continue to rotate. With the gears in this position, pumping cavity 49 is properly positioned relative to the suction and discharge ports in the cap 42 and plate 40 to produce the unidirectional flow in the manner described below. It is noted that thrust plate 4t supports the shaft 15 and interconnected structure through engagement with the underside of gear 46 and must, therefore, be of proper bearing material. Similarly, plate 53 must be of proper bearing material since it is continually compressed between the shaft 15 and gear 46.

Referring again to FIGURE 5, the mating portions of the driving and idler gears in the vicinity of 88 separate the inlet and outlet ports in thrust plate 40. With the driving gear rotating in the counterclockwise direction as shown in FIGURE 5, the suction or low pressure portions of pumping cavity 49 are indicated at 9% and the discharge or high pressure portions of the cavity are indicated at 92. Portions 9i} thus communicate with the suction port 68 in cap 42 while portions 92 communicate with the discharge port 76 therein. As gear 46 rotates in the counterclockwise direction and carries gear 43 along with it, portions fill of cavity 49 are rapidly formed which renders them of low pressure into which the oil from suction port 63 flows. On the other hand, the

oil is compressed in portions 92 of cavity 49 which are also rapidly formed, and is thereby forced throughthe outlet port 76 into the passage 32. It is seen, therefore, that in the operation of the pump, the gears must be so positioned relative to each other that the suction port 68 is in communication with the low pressure portions 90 while the outlet port 76 is in communication with the high pressure portions 92 of cavity 49. The high pressure fluid in portions 92 cannot flow backwardly into portions 90 since the adjacent teeth of the gears are in sliding but sealing contact with each other.

When the gears rotate in a clockwise direction and the outer gear is shifted to the position shown in FIGURE 4 as described above, the low pressure portions 90 are still in communication with the suction port 68 and the high pressure portions 92 are still in communication with the discharge port 76. The result is, therefore, that a unidirectional fiow of oil will be provided by the pump regardless of whether the prime mover of the compressor rotates in a clockwise or counterclockwise direction.

In the modified structure of FIGURES -12, an eccentric gear retainer 94 is identical in shape to retainer 52 except for an upwardly extending shoulder 96 substituted for the notch 66 of retainer 52. The reversing plate 98 is identical in construction to the reversing plate 53 with the exception that tang 84 is omitted to provide a straight shoulder 100 engageable with the shoulder 96 on the retainer 94. It is readily seen that rotation of plate 98 will cause rotation of retainer 94 by virtue of the engagement of shoulders 96 and 100.

As mentioned above, the present invention is not limited in its use to a vertically mounted compressor crankshaft. While it is true that it is structurally and functionally preferable to use the weight of the crankshaft to actuate the clamp-like portions of the reversing device, means other than this weight may be employed. For example, it is readily seen that where the crankshaft is horizontally disposed, spring means could be conveniently located in the unit to exert a proper force on the crankshaft axially thereof to urge the same toward cap 42 to effect the same result as the weight of the crankshaft. Another means would be the purposeful misalignment of the electric motor rotor and the stator which would result in a force component directed axially of the crank shaft.

It is emphasized that the present invention has utility in practically any apparatus which requires a reversible pump, whether the pump be used for pumping lubricant or any other fluid. Moreover, the ruggedness and positive action of the improved reversing device renders it practical in installations where relatively high friction forces may be developed tending to restrain proper operation of the reversing device.

While it will be apparent that the embodiments of the invention herein disclosed are well calculated to fulfill the objects of the invention, it will be appreciated that the invention is susceptible to modification, variation and change without departing from the proper scope or fair meaning of the subjoined claims.

What is claimed is:

1. In a reversible pump having suction and discharge port means communicating with rotary pumping means, a rotatable portion of said pumping means keyed to a rotatable drive shaft and axially movable thereon, a stationary member supporting one side of said rotatable pumping means portion, and reversing means operatively connected to one portion of said pumping means and sandwiched in slidable frictional engagement between the other side of said rotatable pumping means portion and a radial surface on said drive shaft, said reversing means being actuatable in response to changes in the direction of rotation of the drive shaft for shifting said one pumping means portion relative to other portions of said pumping means to maintain unidirectional output of the pump.

2. The construction according to claim 1 wherein said pumping means comprises a pair of meshing driving and idler gears, and wherein said one portion of said pumping means comprises said idler gear.

3. The construction according to claim 2 wherein said driving gear forms part of a thrust bearing assembly for the drive means and supports the full weight thereof.

4. In a reversible rotary type pump having reversing means for shifting portions of the pump in response to a change in the direction of rotation of the pump drive means to thereby maintain unidirectional pump output, carrier means slidably frictionally supporting at least a portion of said reversing means and adapted to rotate the same, said carrier means comprising a pair of fiat surfaces movable toward each other in clamping relationship andbetween which said portion of the reversing means is sandwiched, each of said surfaces being operatively connected to pump drive means for rotation thereby in either direction, said surfaces being adapted for movement toward each other under the weight of the pump drive means.

5. In a reversible pump having a housing provided With suction and discharge port means, relatively rotatable inner and outer pumping gears in said housing, the axes of rotation of said gears being offset from each other to form a pumping cavity communicating with each of said port means, a drive shaft for said pump rotatable in either direction and keyed to said inner gear for rotating the same, said inner gear being axially slidable on said drive shaft, eccentric reversing means engageable with said outer gear, the outer gear being shiftable relative to said inner gear in response to rotation of said eccentric reversing means to shift the position of said pumping cavity to provide unidirectional pump output, and carrier means rotatably supporting at least a portion of said reversing means, said carrier means comprising the upper surface of said inner gear and a laterally extending shoulder on said drive shaft between which said reversing means portion is sandwiched.

References Cited in the file of this patent UNITED STATES PATENTS 1,850,567 Roessler Mar. 22, 1932 2,151,482 Neeson Mar. 21, 1939 2,225,228 Neeson Dec. 17, 1940 2,373,368 Witchger Apr. 10, 1945 2,458,678 Bunte Ian. 11, 1949 2,490,391 Wentling Dec. 6, 1949 2,829,602 Witchger Apr. 8, 1958 2,905,094 Gerteis Sept. 22, 1959 2,956,730 Hamilton et a1 Oct. 18, 1960 3,008,628 Gerteis, et. al. Nov. 14, 1961 FOREIGN PATENTS 463,427 Italy Mar. 29, 1950 7,315 Great Britain Mar. 23, 1914 424,249 Great Britain Oct. 19, 1934 

1. IN A REVERSIBLE PUMP HAVING SUCTION AND DISCHARGE PORT MEANS COMMUNICATING WITH ROTARY PUMPING MEANS, A ROTATABLE PORTION OF SAID PUMPING MEANS KEYED TO A ROTATABLE DRIVE SHAFT AND AXIALLY MOVABLE THEREON, A STATIONARY MEMBER SUPPORTING ONE SIDE OF SAID ROTATABLE PUMPING MEANS PORTION, AND REVERSING MEANS OPERATIVELY CONNECTED TO ONE PORTION OF SAID PUMPING MEANS AND SANDWICHED IN SLIDABLE FRICTIONAL ENGAGEMENT BETWEEN THE OTHER SIDE OF SAID ROTATABLE PUMPING MEANS PORTION AND A RADIAL SURFACE ON SAID DRIVE SHAFT, SAID REVERSING MEANS BEING ACTUATABLE IN RESPONSE TO CHANGES IN THE DIRECTION OF ROTATION OF THE DRIVE SHAFT FOR SHIFTING SAID ONE PUMPING MEANS PORTION RELATIVE TO OTHER PORTIONS OF SAID PUMPING MEANS TO MAINTAIN UNIDIRECTIONAL OUTPUT OF THE PUMP. 